1 /*
2 * Copyright (c) 2001, 2017, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #ifndef SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP
26 #define SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP
27
28 #include "gc/g1/evacuationInfo.hpp"
29 #include "gc/g1/g1AllocationContext.hpp"
30 #include "gc/g1/g1BiasedArray.hpp"
31 #include "gc/g1/g1CollectionSet.hpp"
32 #include "gc/g1/g1CollectorState.hpp"
33 #include "gc/g1/g1ConcurrentMark.hpp"
34 #include "gc/g1/g1EdenRegions.hpp"
35 #include "gc/g1/g1EvacFailure.hpp"
36 #include "gc/g1/g1EvacStats.hpp"
37 #include "gc/g1/g1HeapTransition.hpp"
38 #include "gc/g1/g1HeapVerifier.hpp"
39 #include "gc/g1/g1HRPrinter.hpp"
40 #include "gc/g1/g1InCSetState.hpp"
41 #include "gc/g1/g1MonitoringSupport.hpp"
42 #include "gc/g1/g1SATBCardTableModRefBS.hpp"
43 #include "gc/g1/g1SurvivorRegions.hpp"
44 #include "gc/g1/g1YCTypes.hpp"
45 #include "gc/g1/hSpaceCounters.hpp"
46 #include "gc/g1/heapRegionManager.hpp"
47 #include "gc/g1/heapRegionSet.hpp"
48 #include "gc/shared/barrierSet.hpp"
49 #include "gc/shared/collectedHeap.hpp"
50 #include "gc/shared/plab.hpp"
51 #include "gc/shared/preservedMarks.hpp"
52 #include "memory/memRegion.hpp"
53 #include "utilities/stack.hpp"
54
55 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot.
56 // It uses the "Garbage First" heap organization and algorithm, which
57 // may combine concurrent marking with parallel, incremental compaction of
58 // heap subsets that will yield large amounts of garbage.
59
60 // Forward declarations
61 class HeapRegion;
62 class HRRSCleanupTask;
63 class GenerationSpec;
64 class G1ParScanThreadState;
65 class G1ParScanThreadStateSet;
66 class G1KlassScanClosure;
67 class G1ParScanThreadState;
68 class ObjectClosure;
69 class SpaceClosure;
70 class CompactibleSpaceClosure;
71 class Space;
72 class G1CollectionSet;
73 class G1CollectorPolicy;
74 class G1Policy;
75 class G1HotCardCache;
76 class G1RemSet;
77 class HeapRegionRemSetIterator;
78 class G1ConcurrentMark;
79 class ConcurrentMarkThread;
80 class ConcurrentG1Refine;
81 class GenerationCounters;
82 class STWGCTimer;
83 class G1NewTracer;
84 class EvacuationFailedInfo;
85 class nmethod;
86 class Ticks;
87 class WorkGang;
88 class G1Allocator;
89 class G1ArchiveAllocator;
90 class G1FullGCScope;
91 class G1HeapVerifier;
92 class G1HeapSizingPolicy;
93 class G1HeapSummary;
94 class G1EvacSummary;
95
96 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue;
97 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet;
98
99 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() )
100 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion )
101
102 // The G1 STW is alive closure.
103 // An instance is embedded into the G1CH and used as the
104 // (optional) _is_alive_non_header closure in the STW
105 // reference processor. It is also extensively used during
106 // reference processing during STW evacuation pauses.
107 class G1STWIsAliveClosure: public BoolObjectClosure {
108 G1CollectedHeap* _g1;
109 public:
110 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
111 bool do_object_b(oop p);
112 };
113
114 class G1RegionMappingChangedListener : public G1MappingChangedListener {
115 private:
116 void reset_from_card_cache(uint start_idx, size_t num_regions);
117 public:
118 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled);
119 };
120
121 class G1CollectedHeap : public CollectedHeap {
122 friend class G1FreeCollectionSetTask;
123 friend class VM_CollectForMetadataAllocation;
124 friend class VM_G1CollectForAllocation;
125 friend class VM_G1CollectFull;
126 friend class VM_G1IncCollectionPause;
127 friend class VMStructs;
128 friend class MutatorAllocRegion;
129 friend class G1GCAllocRegion;
130 friend class G1HeapVerifier;
131
132 // Closures used in implementation.
133 friend class G1ParScanThreadState;
134 friend class G1ParScanThreadStateSet;
135 friend class G1ParTask;
136 friend class G1PLABAllocator;
137 friend class G1PrepareCompactClosure;
138
139 // Other related classes.
140 friend class HeapRegionClaimer;
141
142 // Testing classes.
143 friend class G1CheckCSetFastTableClosure;
144
145 private:
146 WorkGang* _workers;
147 G1CollectorPolicy* _collector_policy;
148
149 static size_t _humongous_object_threshold_in_words;
150
151 // The secondary free list which contains regions that have been
152 // freed up during the cleanup process. This will be appended to
153 // the master free list when appropriate.
154 FreeRegionList _secondary_free_list;
155
156 // It keeps track of the old regions.
157 HeapRegionSet _old_set;
158
159 // It keeps track of the humongous regions.
160 HeapRegionSet _humongous_set;
161
162 void eagerly_reclaim_humongous_regions();
163 // Start a new incremental collection set for the next pause.
164 void start_new_collection_set();
165
166 // The number of regions we could create by expansion.
167 uint _expansion_regions;
168
169 // The block offset table for the G1 heap.
170 G1BlockOffsetTable* _bot;
171
172 // Tears down the region sets / lists so that they are empty and the
173 // regions on the heap do not belong to a region set / list. The
174 // only exception is the humongous set which we leave unaltered. If
175 // free_list_only is true, it will only tear down the master free
176 // list. It is called before a Full GC (free_list_only == false) or
177 // before heap shrinking (free_list_only == true).
178 void tear_down_region_sets(bool free_list_only);
179
180 // Rebuilds the region sets / lists so that they are repopulated to
181 // reflect the contents of the heap. The only exception is the
182 // humongous set which was not torn down in the first place. If
183 // free_list_only is true, it will only rebuild the master free
184 // list. It is called after a Full GC (free_list_only == false) or
185 // after heap shrinking (free_list_only == true).
186 void rebuild_region_sets(bool free_list_only);
187
188 // Callback for region mapping changed events.
189 G1RegionMappingChangedListener _listener;
190
191 // The sequence of all heap regions in the heap.
192 HeapRegionManager _hrm;
193
194 // Manages all allocations with regions except humongous object allocations.
195 G1Allocator* _allocator;
196
197 // Manages all heap verification.
198 G1HeapVerifier* _verifier;
199
200 // Outside of GC pauses, the number of bytes used in all regions other
201 // than the current allocation region(s).
202 size_t _summary_bytes_used;
203
204 void increase_used(size_t bytes);
205 void decrease_used(size_t bytes);
206
207 void set_used(size_t bytes);
208
209 // Class that handles archive allocation ranges.
210 G1ArchiveAllocator* _archive_allocator;
211
212 // Statistics for each allocation context
213 AllocationContextStats _allocation_context_stats;
214
215 // GC allocation statistics policy for survivors.
216 G1EvacStats _survivor_evac_stats;
217
218 // GC allocation statistics policy for tenured objects.
219 G1EvacStats _old_evac_stats;
220
221 // It specifies whether we should attempt to expand the heap after a
222 // region allocation failure. If heap expansion fails we set this to
223 // false so that we don't re-attempt the heap expansion (it's likely
224 // that subsequent expansion attempts will also fail if one fails).
225 // Currently, it is only consulted during GC and it's reset at the
226 // start of each GC.
227 bool _expand_heap_after_alloc_failure;
228
229 // Helper for monitoring and management support.
230 G1MonitoringSupport* _g1mm;
231
232 // Records whether the region at the given index is (still) a
233 // candidate for eager reclaim. Only valid for humongous start
234 // regions; other regions have unspecified values. Humongous start
235 // regions are initialized at start of collection pause, with
236 // candidates removed from the set as they are found reachable from
237 // roots or the young generation.
238 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> {
239 protected:
240 bool default_value() const { return false; }
241 public:
242 void clear() { G1BiasedMappedArray<bool>::clear(); }
243 void set_candidate(uint region, bool value) {
244 set_by_index(region, value);
245 }
246 bool is_candidate(uint region) {
247 return get_by_index(region);
248 }
249 };
250
251 HumongousReclaimCandidates _humongous_reclaim_candidates;
252 // Stores whether during humongous object registration we found candidate regions.
253 // If not, we can skip a few steps.
254 bool _has_humongous_reclaim_candidates;
255
256 volatile uint _gc_time_stamp;
257
258 G1HRPrinter _hr_printer;
259
260 // It decides whether an explicit GC should start a concurrent cycle
261 // instead of doing a STW GC. Currently, a concurrent cycle is
262 // explicitly started if:
263 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or
264 // (b) cause == _g1_humongous_allocation
265 // (c) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent.
266 // (d) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent.
267 // (e) cause == _update_allocation_context_stats_inc
268 // (f) cause == _wb_conc_mark
269 bool should_do_concurrent_full_gc(GCCause::Cause cause);
270
271 // indicates whether we are in young or mixed GC mode
272 G1CollectorState _collector_state;
273
274 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
275 // concurrent cycles) we have started.
276 volatile uint _old_marking_cycles_started;
277
278 // Keeps track of how many "old marking cycles" (i.e., Full GCs or
279 // concurrent cycles) we have completed.
280 volatile uint _old_marking_cycles_completed;
281
282 // This is a non-product method that is helpful for testing. It is
283 // called at the end of a GC and artificially expands the heap by
284 // allocating a number of dead regions. This way we can induce very
285 // frequent marking cycles and stress the cleanup / concurrent
286 // cleanup code more (as all the regions that will be allocated by
287 // this method will be found dead by the marking cycle).
288 void allocate_dummy_regions() PRODUCT_RETURN;
289
290 // Clear RSets after a compaction. It also resets the GC time stamps.
291 void clear_rsets_post_compaction();
292
293 // If the HR printer is active, dump the state of the regions in the
294 // heap after a compaction.
295 void print_hrm_post_compaction();
296
297 // Create a memory mapper for auxiliary data structures of the given size and
298 // translation factor.
299 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description,
300 size_t size,
301 size_t translation_factor);
302
303 static G1Policy* create_g1_policy(STWGCTimer* gc_timer);
304
305 void trace_heap(GCWhen::Type when, const GCTracer* tracer);
306
307 void process_heap_monitoring();
308 void process_weak_jni_handles();
309
310 // These are macros so that, if the assert fires, we get the correct
311 // line number, file, etc.
312
313 #define heap_locking_asserts_params(_extra_message_) \
314 "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \
315 (_extra_message_), \
316 BOOL_TO_STR(Heap_lock->owned_by_self()), \
317 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \
318 BOOL_TO_STR(Thread::current()->is_VM_thread())
319
320 #define assert_heap_locked() \
321 do { \
322 assert(Heap_lock->owned_by_self(), \
323 heap_locking_asserts_params("should be holding the Heap_lock")); \
324 } while (0)
325
326 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \
327 do { \
328 assert(Heap_lock->owned_by_self() || \
329 (SafepointSynchronize::is_at_safepoint() && \
330 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \
331 heap_locking_asserts_params("should be holding the Heap_lock or " \
332 "should be at a safepoint")); \
333 } while (0)
334
335 #define assert_heap_locked_and_not_at_safepoint() \
336 do { \
337 assert(Heap_lock->owned_by_self() && \
338 !SafepointSynchronize::is_at_safepoint(), \
339 heap_locking_asserts_params("should be holding the Heap_lock and " \
340 "should not be at a safepoint")); \
341 } while (0)
342
343 #define assert_heap_not_locked() \
344 do { \
345 assert(!Heap_lock->owned_by_self(), \
346 heap_locking_asserts_params("should not be holding the Heap_lock")); \
347 } while (0)
348
349 #define assert_heap_not_locked_and_not_at_safepoint() \
350 do { \
351 assert(!Heap_lock->owned_by_self() && \
352 !SafepointSynchronize::is_at_safepoint(), \
353 heap_locking_asserts_params("should not be holding the Heap_lock and " \
354 "should not be at a safepoint")); \
355 } while (0)
356
357 #define assert_at_safepoint(_should_be_vm_thread_) \
358 do { \
359 assert(SafepointSynchronize::is_at_safepoint() && \
360 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \
361 heap_locking_asserts_params("should be at a safepoint")); \
362 } while (0)
363
364 #define assert_not_at_safepoint() \
365 do { \
366 assert(!SafepointSynchronize::is_at_safepoint(), \
367 heap_locking_asserts_params("should not be at a safepoint")); \
368 } while (0)
369
370 protected:
371
372 // The young region list.
373 G1EdenRegions _eden;
374 G1SurvivorRegions _survivor;
375
376 STWGCTimer* _gc_timer_stw;
377
378 G1NewTracer* _gc_tracer_stw;
379
380 // The current policy object for the collector.
381 G1Policy* _g1_policy;
382 G1HeapSizingPolicy* _heap_sizing_policy;
383
384 G1CollectionSet _collection_set;
385
386 // This is the second level of trying to allocate a new region. If
387 // new_region() didn't find a region on the free_list, this call will
388 // check whether there's anything available on the
389 // secondary_free_list and/or wait for more regions to appear on
390 // that list, if _free_regions_coming is set.
391 HeapRegion* new_region_try_secondary_free_list(bool is_old);
392
393 // Try to allocate a single non-humongous HeapRegion sufficient for
394 // an allocation of the given word_size. If do_expand is true,
395 // attempt to expand the heap if necessary to satisfy the allocation
396 // request. If the region is to be used as an old region or for a
397 // humongous object, set is_old to true. If not, to false.
398 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand);
399
400 // Initialize a contiguous set of free regions of length num_regions
401 // and starting at index first so that they appear as a single
402 // humongous region.
403 HeapWord* humongous_obj_allocate_initialize_regions(uint first,
404 uint num_regions,
405 size_t word_size,
406 AllocationContext_t context);
407
408 // Attempt to allocate a humongous object of the given size. Return
409 // NULL if unsuccessful.
410 HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context);
411
412 // The following two methods, allocate_new_tlab() and
413 // mem_allocate(), are the two main entry points from the runtime
414 // into the G1's allocation routines. They have the following
415 // assumptions:
416 //
417 // * They should both be called outside safepoints.
418 //
419 // * They should both be called without holding the Heap_lock.
420 //
421 // * All allocation requests for new TLABs should go to
422 // allocate_new_tlab().
423 //
424 // * All non-TLAB allocation requests should go to mem_allocate().
425 //
426 // * If either call cannot satisfy the allocation request using the
427 // current allocating region, they will try to get a new one. If
428 // this fails, they will attempt to do an evacuation pause and
429 // retry the allocation.
430 //
431 // * If all allocation attempts fail, even after trying to schedule
432 // an evacuation pause, allocate_new_tlab() will return NULL,
433 // whereas mem_allocate() will attempt a heap expansion and/or
434 // schedule a Full GC.
435 //
436 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab
437 // should never be called with word_size being humongous. All
438 // humongous allocation requests should go to mem_allocate() which
439 // will satisfy them with a special path.
440
441 virtual HeapWord* allocate_new_tlab(size_t word_size);
442
443 virtual HeapWord* mem_allocate(size_t word_size,
444 bool* gc_overhead_limit_was_exceeded);
445
446 // The following three methods take a gc_count_before_ret
447 // parameter which is used to return the GC count if the method
448 // returns NULL. Given that we are required to read the GC count
449 // while holding the Heap_lock, and these paths will take the
450 // Heap_lock at some point, it's easier to get them to read the GC
451 // count while holding the Heap_lock before they return NULL instead
452 // of the caller (namely: mem_allocate()) having to also take the
453 // Heap_lock just to read the GC count.
454
455 // First-level mutator allocation attempt: try to allocate out of
456 // the mutator alloc region without taking the Heap_lock. This
457 // should only be used for non-humongous allocations.
458 inline HeapWord* attempt_allocation(size_t word_size,
459 uint* gc_count_before_ret,
460 uint* gclocker_retry_count_ret);
461
462 // Second-level mutator allocation attempt: take the Heap_lock and
463 // retry the allocation attempt, potentially scheduling a GC
464 // pause. This should only be used for non-humongous allocations.
465 HeapWord* attempt_allocation_slow(size_t word_size,
466 AllocationContext_t context,
467 uint* gc_count_before_ret,
468 uint* gclocker_retry_count_ret);
469
470 // Takes the Heap_lock and attempts a humongous allocation. It can
471 // potentially schedule a GC pause.
472 HeapWord* attempt_allocation_humongous(size_t word_size,
473 uint* gc_count_before_ret,
474 uint* gclocker_retry_count_ret);
475
476 // Allocation attempt that should be called during safepoints (e.g.,
477 // at the end of a successful GC). expect_null_mutator_alloc_region
478 // specifies whether the mutator alloc region is expected to be NULL
479 // or not.
480 HeapWord* attempt_allocation_at_safepoint(size_t word_size,
481 AllocationContext_t context,
482 bool expect_null_mutator_alloc_region);
483
484 // These methods are the "callbacks" from the G1AllocRegion class.
485
486 // For mutator alloc regions.
487 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force);
488 void retire_mutator_alloc_region(HeapRegion* alloc_region,
489 size_t allocated_bytes);
490
491 // For GC alloc regions.
492 bool has_more_regions(InCSetState dest);
493 HeapRegion* new_gc_alloc_region(size_t word_size, InCSetState dest);
494 void retire_gc_alloc_region(HeapRegion* alloc_region,
495 size_t allocated_bytes, InCSetState dest);
496
497 // - if explicit_gc is true, the GC is for a System.gc() etc,
498 // otherwise it's for a failed allocation.
499 // - if clear_all_soft_refs is true, all soft references should be
500 // cleared during the GC.
501 // - it returns false if it is unable to do the collection due to the
502 // GC locker being active, true otherwise.
503 bool do_full_collection(bool explicit_gc,
504 bool clear_all_soft_refs);
505
506 // Callback from VM_G1CollectFull operation, or collect_as_vm_thread.
507 virtual void do_full_collection(bool clear_all_soft_refs);
508
509 // Resize the heap if necessary after a full collection.
510 void resize_if_necessary_after_full_collection();
511
512 // Callback from VM_G1CollectForAllocation operation.
513 // This function does everything necessary/possible to satisfy a
514 // failed allocation request (including collection, expansion, etc.)
515 HeapWord* satisfy_failed_allocation(size_t word_size,
516 AllocationContext_t context,
517 bool* succeeded);
518 private:
519 // Internal helpers used during full GC to split it up to
520 // increase readability.
521 void do_full_collection_inner(G1FullGCScope* scope);
522 void abort_concurrent_cycle();
523 void verify_before_full_collection(bool explicit_gc);
524 void prepare_heap_for_full_collection();
525 void prepare_heap_for_mutators();
526 void abort_refinement();
527 void verify_after_full_collection();
528 void print_heap_after_full_collection(G1HeapTransition* heap_transition);
529
530 // Helper method for satisfy_failed_allocation()
531 HeapWord* satisfy_failed_allocation_helper(size_t word_size,
532 AllocationContext_t context,
533 bool do_gc,
534 bool clear_all_soft_refs,
535 bool expect_null_mutator_alloc_region,
536 bool* gc_succeeded);
537
538 protected:
539 // Attempting to expand the heap sufficiently
540 // to support an allocation of the given "word_size". If
541 // successful, perform the allocation and return the address of the
542 // allocated block, or else "NULL".
543 HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context);
544
545 // Preserve any referents discovered by concurrent marking that have not yet been
546 // copied by the STW pause.
547 void preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states);
548 // Process any reference objects discovered during
549 // an incremental evacuation pause.
550 void process_discovered_references(G1ParScanThreadStateSet* per_thread_states);
551
552 // Enqueue any remaining discovered references
553 // after processing.
554 void enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states);
555
556 // Merges the information gathered on a per-thread basis for all worker threads
557 // during GC into global variables.
558 void merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states);
559 public:
560 WorkGang* workers() const { return _workers; }
561
562 G1Allocator* allocator() {
563 return _allocator;
564 }
565
566 G1HeapVerifier* verifier() {
567 return _verifier;
568 }
569
570 G1MonitoringSupport* g1mm() {
571 assert(_g1mm != NULL, "should have been initialized");
572 return _g1mm;
573 }
574
575 // Expand the garbage-first heap by at least the given size (in bytes!).
576 // Returns true if the heap was expanded by the requested amount;
577 // false otherwise.
578 // (Rounds up to a HeapRegion boundary.)
579 bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL);
580
581 // Returns the PLAB statistics for a given destination.
582 inline G1EvacStats* alloc_buffer_stats(InCSetState dest);
583
584 // Determines PLAB size for a given destination.
585 inline size_t desired_plab_sz(InCSetState dest);
586
587 inline AllocationContextStats& allocation_context_stats();
588
589 // Do anything common to GC's.
590 void gc_prologue(bool full);
591 void gc_epilogue(bool full);
592
593 // Modify the reclaim candidate set and test for presence.
594 // These are only valid for starts_humongous regions.
595 inline void set_humongous_reclaim_candidate(uint region, bool value);
596 inline bool is_humongous_reclaim_candidate(uint region);
597
598 // Remove from the reclaim candidate set. Also remove from the
599 // collection set so that later encounters avoid the slow path.
600 inline void set_humongous_is_live(oop obj);
601
602 // Register the given region to be part of the collection set.
603 inline void register_humongous_region_with_cset(uint index);
604 // Register regions with humongous objects (actually on the start region) in
605 // the in_cset_fast_test table.
606 void register_humongous_regions_with_cset();
607 // We register a region with the fast "in collection set" test. We
608 // simply set to true the array slot corresponding to this region.
609 void register_young_region_with_cset(HeapRegion* r) {
610 _in_cset_fast_test.set_in_young(r->hrm_index());
611 }
612 void register_old_region_with_cset(HeapRegion* r) {
613 _in_cset_fast_test.set_in_old(r->hrm_index());
614 }
615 inline void register_ext_region_with_cset(HeapRegion* r) {
616 _in_cset_fast_test.set_ext(r->hrm_index());
617 }
618 void clear_in_cset(const HeapRegion* hr) {
619 _in_cset_fast_test.clear(hr);
620 }
621
622 void clear_cset_fast_test() {
623 _in_cset_fast_test.clear();
624 }
625
626 bool is_user_requested_concurrent_full_gc(GCCause::Cause cause);
627
628 // This is called at the start of either a concurrent cycle or a Full
629 // GC to update the number of old marking cycles started.
630 void increment_old_marking_cycles_started();
631
632 // This is called at the end of either a concurrent cycle or a Full
633 // GC to update the number of old marking cycles completed. Those two
634 // can happen in a nested fashion, i.e., we start a concurrent
635 // cycle, a Full GC happens half-way through it which ends first,
636 // and then the cycle notices that a Full GC happened and ends
637 // too. The concurrent parameter is a boolean to help us do a bit
638 // tighter consistency checking in the method. If concurrent is
639 // false, the caller is the inner caller in the nesting (i.e., the
640 // Full GC). If concurrent is true, the caller is the outer caller
641 // in this nesting (i.e., the concurrent cycle). Further nesting is
642 // not currently supported. The end of this call also notifies
643 // the FullGCCount_lock in case a Java thread is waiting for a full
644 // GC to happen (e.g., it called System.gc() with
645 // +ExplicitGCInvokesConcurrent).
646 void increment_old_marking_cycles_completed(bool concurrent);
647
648 uint old_marking_cycles_completed() {
649 return _old_marking_cycles_completed;
650 }
651
652 G1HRPrinter* hr_printer() { return &_hr_printer; }
653
654 // Allocates a new heap region instance.
655 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr);
656
657 // Allocate the highest free region in the reserved heap. This will commit
658 // regions as necessary.
659 HeapRegion* alloc_highest_free_region();
660
661 // Frees a non-humongous region by initializing its contents and
662 // adding it to the free list that's passed as a parameter (this is
663 // usually a local list which will be appended to the master free
664 // list later). The used bytes of freed regions are accumulated in
665 // pre_used. If skip_remset is true, the region's RSet will not be freed
666 // up. If skip_hot_card_cache is true, the region's hot card cache will not
667 // be freed up. The assumption is that this will be done later.
668 // The locked parameter indicates if the caller has already taken
669 // care of proper synchronization. This may allow some optimizations.
670 void free_region(HeapRegion* hr,
671 FreeRegionList* free_list,
672 bool skip_remset,
673 bool skip_hot_card_cache = false,
674 bool locked = false);
675
676 // It dirties the cards that cover the block so that the post
677 // write barrier never queues anything when updating objects on this
678 // block. It is assumed (and in fact we assert) that the block
679 // belongs to a young region.
680 inline void dirty_young_block(HeapWord* start, size_t word_size);
681
682 // Frees a humongous region by collapsing it into individual regions
683 // and calling free_region() for each of them. The freed regions
684 // will be added to the free list that's passed as a parameter (this
685 // is usually a local list which will be appended to the master free
686 // list later). The used bytes of freed regions are accumulated in
687 // pre_used. If skip_remset is true, the region's RSet will not be freed
688 // up. The assumption is that this will be done later.
689 void free_humongous_region(HeapRegion* hr,
690 FreeRegionList* free_list,
691 bool skip_remset);
692
693 // Facility for allocating in 'archive' regions in high heap memory and
694 // recording the allocated ranges. These should all be called from the
695 // VM thread at safepoints, without the heap lock held. They can be used
696 // to create and archive a set of heap regions which can be mapped at the
697 // same fixed addresses in a subsequent JVM invocation.
698 void begin_archive_alloc_range(bool open = false);
699
700 // Check if the requested size would be too large for an archive allocation.
701 bool is_archive_alloc_too_large(size_t word_size);
702
703 // Allocate memory of the requested size from the archive region. This will
704 // return NULL if the size is too large or if no memory is available. It
705 // does not trigger a garbage collection.
706 HeapWord* archive_mem_allocate(size_t word_size);
707
708 // Optionally aligns the end address and returns the allocated ranges in
709 // an array of MemRegions in order of ascending addresses.
710 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
711 size_t end_alignment_in_bytes = 0);
712
713 // Facility for allocating a fixed range within the heap and marking
714 // the containing regions as 'archive'. For use at JVM init time, when the
715 // caller may mmap archived heap data at the specified range(s).
716 // Verify that the MemRegions specified in the argument array are within the
717 // reserved heap.
718 bool check_archive_addresses(MemRegion* range, size_t count);
719
720 // Commit the appropriate G1 regions containing the specified MemRegions
721 // and mark them as 'archive' regions. The regions in the array must be
722 // non-overlapping and in order of ascending address.
723 bool alloc_archive_regions(MemRegion* range, size_t count, bool open);
724
725 // Insert any required filler objects in the G1 regions around the specified
726 // ranges to make the regions parseable. This must be called after
727 // alloc_archive_regions, and after class loading has occurred.
728 void fill_archive_regions(MemRegion* range, size_t count);
729
730 // For each of the specified MemRegions, uncommit the containing G1 regions
731 // which had been allocated by alloc_archive_regions. This should be called
732 // rather than fill_archive_regions at JVM init time if the archive file
733 // mapping failed, with the same non-overlapping and sorted MemRegion array.
734 void dealloc_archive_regions(MemRegion* range, size_t count);
735
736 protected:
737
738 // Shrink the garbage-first heap by at most the given size (in bytes!).
739 // (Rounds down to a HeapRegion boundary.)
740 virtual void shrink(size_t expand_bytes);
741 void shrink_helper(size_t expand_bytes);
742
743 #if TASKQUEUE_STATS
744 static void print_taskqueue_stats_hdr(outputStream* const st);
745 void print_taskqueue_stats() const;
746 void reset_taskqueue_stats();
747 #endif // TASKQUEUE_STATS
748
749 // Schedule the VM operation that will do an evacuation pause to
750 // satisfy an allocation request of word_size. *succeeded will
751 // return whether the VM operation was successful (it did do an
752 // evacuation pause) or not (another thread beat us to it or the GC
753 // locker was active). Given that we should not be holding the
754 // Heap_lock when we enter this method, we will pass the
755 // gc_count_before (i.e., total_collections()) as a parameter since
756 // it has to be read while holding the Heap_lock. Currently, both
757 // methods that call do_collection_pause() release the Heap_lock
758 // before the call, so it's easy to read gc_count_before just before.
759 HeapWord* do_collection_pause(size_t word_size,
760 uint gc_count_before,
761 bool* succeeded,
762 GCCause::Cause gc_cause);
763
764 void wait_for_root_region_scanning();
765
766 // The guts of the incremental collection pause, executed by the vm
767 // thread. It returns false if it is unable to do the collection due
768 // to the GC locker being active, true otherwise
769 bool do_collection_pause_at_safepoint(double target_pause_time_ms);
770
771 // Actually do the work of evacuating the collection set.
772 virtual void evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states);
773
774 void pre_evacuate_collection_set();
775 void post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss);
776
777 // Print the header for the per-thread termination statistics.
778 static void print_termination_stats_hdr();
779 // Print actual per-thread termination statistics.
780 void print_termination_stats(uint worker_id,
781 double elapsed_ms,
782 double strong_roots_ms,
783 double term_ms,
784 size_t term_attempts,
785 size_t alloc_buffer_waste,
786 size_t undo_waste) const;
787 // Update object copying statistics.
788 void record_obj_copy_mem_stats();
789
790 // The hot card cache for remembered set insertion optimization.
791 G1HotCardCache* _hot_card_cache;
792
793 // The g1 remembered set of the heap.
794 G1RemSet* _g1_rem_set;
795
796 // A set of cards that cover the objects for which the Rsets should be updated
797 // concurrently after the collection.
798 DirtyCardQueueSet _dirty_card_queue_set;
799
800 // After a collection pause, convert the regions in the collection set into free
801 // regions.
802 void free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words);
803
804 // Abandon the current collection set without recording policy
805 // statistics or updating free lists.
806 void abandon_collection_set(G1CollectionSet* collection_set);
807
808 // The concurrent marker (and the thread it runs in.)
809 G1ConcurrentMark* _cm;
810 ConcurrentMarkThread* _cmThread;
811
812 // The concurrent refiner.
813 ConcurrentG1Refine* _cg1r;
814
815 // The parallel task queues
816 RefToScanQueueSet *_task_queues;
817
818 // True iff a evacuation has failed in the current collection.
819 bool _evacuation_failed;
820
821 EvacuationFailedInfo* _evacuation_failed_info_array;
822
823 // Failed evacuations cause some logical from-space objects to have
824 // forwarding pointers to themselves. Reset them.
825 void remove_self_forwarding_pointers();
826
827 // Restore the objects in the regions in the collection set after an
828 // evacuation failure.
829 void restore_after_evac_failure();
830
831 PreservedMarksSet _preserved_marks_set;
832
833 // Preserve the mark of "obj", if necessary, in preparation for its mark
834 // word being overwritten with a self-forwarding-pointer.
835 void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m);
836
837 #ifndef PRODUCT
838 // Support for forcing evacuation failures. Analogous to
839 // PromotionFailureALot for the other collectors.
840
841 // Records whether G1EvacuationFailureALot should be in effect
842 // for the current GC
843 bool _evacuation_failure_alot_for_current_gc;
844
845 // Used to record the GC number for interval checking when
846 // determining whether G1EvaucationFailureALot is in effect
847 // for the current GC.
848 size_t _evacuation_failure_alot_gc_number;
849
850 // Count of the number of evacuations between failures.
851 volatile size_t _evacuation_failure_alot_count;
852
853 // Set whether G1EvacuationFailureALot should be in effect
854 // for the current GC (based upon the type of GC and which
855 // command line flags are set);
856 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young,
857 bool during_initial_mark,
858 bool during_marking);
859
860 inline void set_evacuation_failure_alot_for_current_gc();
861
862 // Return true if it's time to cause an evacuation failure.
863 inline bool evacuation_should_fail();
864
865 // Reset the G1EvacuationFailureALot counters. Should be called at
866 // the end of an evacuation pause in which an evacuation failure occurred.
867 inline void reset_evacuation_should_fail();
868 #endif // !PRODUCT
869
870 // ("Weak") Reference processing support.
871 //
872 // G1 has 2 instances of the reference processor class. One
873 // (_ref_processor_cm) handles reference object discovery
874 // and subsequent processing during concurrent marking cycles.
875 //
876 // The other (_ref_processor_stw) handles reference object
877 // discovery and processing during full GCs and incremental
878 // evacuation pauses.
879 //
880 // During an incremental pause, reference discovery will be
881 // temporarily disabled for _ref_processor_cm and will be
882 // enabled for _ref_processor_stw. At the end of the evacuation
883 // pause references discovered by _ref_processor_stw will be
884 // processed and discovery will be disabled. The previous
885 // setting for reference object discovery for _ref_processor_cm
886 // will be re-instated.
887 //
888 // At the start of marking:
889 // * Discovery by the CM ref processor is verified to be inactive
890 // and it's discovered lists are empty.
891 // * Discovery by the CM ref processor is then enabled.
892 //
893 // At the end of marking:
894 // * Any references on the CM ref processor's discovered
895 // lists are processed (possibly MT).
896 //
897 // At the start of full GC we:
898 // * Disable discovery by the CM ref processor and
899 // empty CM ref processor's discovered lists
900 // (without processing any entries).
901 // * Verify that the STW ref processor is inactive and it's
902 // discovered lists are empty.
903 // * Temporarily set STW ref processor discovery as single threaded.
904 // * Temporarily clear the STW ref processor's _is_alive_non_header
905 // field.
906 // * Finally enable discovery by the STW ref processor.
907 //
908 // The STW ref processor is used to record any discovered
909 // references during the full GC.
910 //
911 // At the end of a full GC we:
912 // * Enqueue any reference objects discovered by the STW ref processor
913 // that have non-live referents. This has the side-effect of
914 // making the STW ref processor inactive by disabling discovery.
915 // * Verify that the CM ref processor is still inactive
916 // and no references have been placed on it's discovered
917 // lists (also checked as a precondition during initial marking).
918
919 // The (stw) reference processor...
920 ReferenceProcessor* _ref_processor_stw;
921
922 // During reference object discovery, the _is_alive_non_header
923 // closure (if non-null) is applied to the referent object to
924 // determine whether the referent is live. If so then the
925 // reference object does not need to be 'discovered' and can
926 // be treated as a regular oop. This has the benefit of reducing
927 // the number of 'discovered' reference objects that need to
928 // be processed.
929 //
930 // Instance of the is_alive closure for embedding into the
931 // STW reference processor as the _is_alive_non_header field.
932 // Supplying a value for the _is_alive_non_header field is
933 // optional but doing so prevents unnecessary additions to
934 // the discovered lists during reference discovery.
935 G1STWIsAliveClosure _is_alive_closure_stw;
936
937 // The (concurrent marking) reference processor...
938 ReferenceProcessor* _ref_processor_cm;
939
940 // Instance of the concurrent mark is_alive closure for embedding
941 // into the Concurrent Marking reference processor as the
942 // _is_alive_non_header field. Supplying a value for the
943 // _is_alive_non_header field is optional but doing so prevents
944 // unnecessary additions to the discovered lists during reference
945 // discovery.
946 G1CMIsAliveClosure _is_alive_closure_cm;
947
948 volatile bool _free_regions_coming;
949
950 public:
951
952 RefToScanQueue *task_queue(uint i) const;
953
954 uint num_task_queues() const;
955
956 // A set of cards where updates happened during the GC
957 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; }
958
959 // Create a G1CollectedHeap with the specified policy.
960 // Must call the initialize method afterwards.
961 // May not return if something goes wrong.
962 G1CollectedHeap(G1CollectorPolicy* policy);
963
964 private:
965 jint initialize_concurrent_refinement();
966 public:
967 // Initialize the G1CollectedHeap to have the initial and
968 // maximum sizes and remembered and barrier sets
969 // specified by the policy object.
970 jint initialize();
971
972 virtual void stop();
973
974 // Return the (conservative) maximum heap alignment for any G1 heap
975 static size_t conservative_max_heap_alignment();
976
977 // Does operations required after initialization has been done.
978 void post_initialize();
979
980 // Initialize weak reference processing.
981 void ref_processing_init();
982
983 virtual Name kind() const {
984 return CollectedHeap::G1CollectedHeap;
985 }
986
987 virtual const char* name() const {
988 return "G1";
989 }
990
991 const G1CollectorState* collector_state() const { return &_collector_state; }
992 G1CollectorState* collector_state() { return &_collector_state; }
993
994 // The current policy object for the collector.
995 G1Policy* g1_policy() const { return _g1_policy; }
996
997 const G1CollectionSet* collection_set() const { return &_collection_set; }
998 G1CollectionSet* collection_set() { return &_collection_set; }
999
1000 virtual CollectorPolicy* collector_policy() const;
1001
1002 // Adaptive size policy. No such thing for g1.
1003 virtual AdaptiveSizePolicy* size_policy() { return NULL; }
1004
1005 // The rem set and barrier set.
1006 G1RemSet* g1_rem_set() const { return _g1_rem_set; }
1007
1008 // Try to minimize the remembered set.
1009 void scrub_rem_set();
1010
1011 uint get_gc_time_stamp() {
1012 return _gc_time_stamp;
1013 }
1014
1015 inline void reset_gc_time_stamp();
1016
1017 void check_gc_time_stamps() PRODUCT_RETURN;
1018
1019 inline void increment_gc_time_stamp();
1020
1021 // Reset the given region's GC timestamp. If it's starts humongous,
1022 // also reset the GC timestamp of its corresponding
1023 // continues humongous regions too.
1024 void reset_gc_time_stamps(HeapRegion* hr);
1025
1026 // Apply the given closure on all cards in the Hot Card Cache, emptying it.
1027 void iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i);
1028
1029 // Apply the given closure on all cards in the Dirty Card Queue Set, emptying it.
1030 void iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i);
1031
1032 // The shared block offset table array.
1033 G1BlockOffsetTable* bot() const { return _bot; }
1034
1035 // Reference Processing accessors
1036
1037 // The STW reference processor....
1038 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; }
1039
1040 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; }
1041
1042 // The Concurrent Marking reference processor...
1043 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; }
1044
1045 virtual size_t capacity() const;
1046 virtual size_t used() const;
1047 // This should be called when we're not holding the heap lock. The
1048 // result might be a bit inaccurate.
1049 size_t used_unlocked() const;
1050 size_t recalculate_used() const;
1051
1052 // These virtual functions do the actual allocation.
1053 // Some heaps may offer a contiguous region for shared non-blocking
1054 // allocation, via inlined code (by exporting the address of the top and
1055 // end fields defining the extent of the contiguous allocation region.)
1056 // But G1CollectedHeap doesn't yet support this.
1057
1058 virtual bool is_maximal_no_gc() const {
1059 return _hrm.available() == 0;
1060 }
1061
1062 // The current number of regions in the heap.
1063 uint num_regions() const { return _hrm.length(); }
1064
1065 // The max number of regions in the heap.
1066 uint max_regions() const { return _hrm.max_length(); }
1067
1068 // The number of regions that are completely free.
1069 uint num_free_regions() const { return _hrm.num_free_regions(); }
1070
1071 MemoryUsage get_auxiliary_data_memory_usage() const {
1072 return _hrm.get_auxiliary_data_memory_usage();
1073 }
1074
1075 // The number of regions that are not completely free.
1076 uint num_used_regions() const { return num_regions() - num_free_regions(); }
1077
1078 #ifdef ASSERT
1079 bool is_on_master_free_list(HeapRegion* hr) {
1080 return _hrm.is_free(hr);
1081 }
1082 #endif // ASSERT
1083
1084 // Wrapper for the region list operations that can be called from
1085 // methods outside this class.
1086
1087 void secondary_free_list_add(FreeRegionList* list) {
1088 _secondary_free_list.add_ordered(list);
1089 }
1090
1091 void append_secondary_free_list() {
1092 _hrm.insert_list_into_free_list(&_secondary_free_list);
1093 }
1094
1095 void append_secondary_free_list_if_not_empty_with_lock() {
1096 // If the secondary free list looks empty there's no reason to
1097 // take the lock and then try to append it.
1098 if (!_secondary_free_list.is_empty()) {
1099 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
1100 append_secondary_free_list();
1101 }
1102 }
1103
1104 inline void old_set_add(HeapRegion* hr);
1105 inline void old_set_remove(HeapRegion* hr);
1106
1107 size_t non_young_capacity_bytes() {
1108 return (_old_set.length() + _humongous_set.length()) * HeapRegion::GrainBytes;
1109 }
1110
1111 void set_free_regions_coming();
1112 void reset_free_regions_coming();
1113 bool free_regions_coming() { return _free_regions_coming; }
1114 void wait_while_free_regions_coming();
1115
1116 // Determine whether the given region is one that we are using as an
1117 // old GC alloc region.
1118 bool is_old_gc_alloc_region(HeapRegion* hr);
1119
1120 // Perform a collection of the heap; intended for use in implementing
1121 // "System.gc". This probably implies as full a collection as the
1122 // "CollectedHeap" supports.
1123 virtual void collect(GCCause::Cause cause);
1124
1125 virtual bool copy_allocation_context_stats(const jint* contexts,
1126 jlong* totals,
1127 jbyte* accuracy,
1128 jint len);
1129
1130 // True iff an evacuation has failed in the most-recent collection.
1131 bool evacuation_failed() { return _evacuation_failed; }
1132
1133 void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed);
1134 void prepend_to_freelist(FreeRegionList* list);
1135 void decrement_summary_bytes(size_t bytes);
1136
1137 virtual bool is_in(const void* p) const;
1138 #ifdef ASSERT
1139 // Returns whether p is in one of the available areas of the heap. Slow but
1140 // extensive version.
1141 bool is_in_exact(const void* p) const;
1142 #endif
1143
1144 // Return "TRUE" iff the given object address is within the collection
1145 // set. Assumes that the reference points into the heap.
1146 inline bool is_in_cset(const HeapRegion *hr);
1147 inline bool is_in_cset(oop obj);
1148 inline bool is_in_cset(HeapWord* addr);
1149
1150 inline bool is_in_cset_or_humongous(const oop obj);
1151
1152 private:
1153 // This array is used for a quick test on whether a reference points into
1154 // the collection set or not. Each of the array's elements denotes whether the
1155 // corresponding region is in the collection set or not.
1156 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test;
1157
1158 public:
1159
1160 inline InCSetState in_cset_state(const oop obj);
1161
1162 // Return "TRUE" iff the given object address is in the reserved
1163 // region of g1.
1164 bool is_in_g1_reserved(const void* p) const {
1165 return _hrm.reserved().contains(p);
1166 }
1167
1168 // Returns a MemRegion that corresponds to the space that has been
1169 // reserved for the heap
1170 MemRegion g1_reserved() const {
1171 return _hrm.reserved();
1172 }
1173
1174 virtual bool is_in_closed_subset(const void* p) const;
1175
1176 G1SATBCardTableLoggingModRefBS* g1_barrier_set() {
1177 return barrier_set_cast<G1SATBCardTableLoggingModRefBS>(barrier_set());
1178 }
1179
1180 // Iteration functions.
1181
1182 // Iterate over all objects, calling "cl.do_object" on each.
1183 virtual void object_iterate(ObjectClosure* cl);
1184
1185 virtual void safe_object_iterate(ObjectClosure* cl) {
1186 object_iterate(cl);
1187 }
1188
1189 // Iterate over heap regions, in address order, terminating the
1190 // iteration early if the "doHeapRegion" method returns "true".
1191 void heap_region_iterate(HeapRegionClosure* blk) const;
1192
1193 // Return the region with the given index. It assumes the index is valid.
1194 inline HeapRegion* region_at(uint index) const;
1195
1196 // Return the next region (by index) that is part of the same
1197 // humongous object that hr is part of.
1198 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const;
1199
1200 // Calculate the region index of the given address. Given address must be
1201 // within the heap.
1202 inline uint addr_to_region(HeapWord* addr) const;
1203
1204 inline HeapWord* bottom_addr_for_region(uint index) const;
1205
1206 // Iterate over the heap regions in parallel. Assumes that this will be called
1207 // in parallel by a number of worker threads with distinct worker ids
1208 // in the range passed to the HeapRegionClaimer. Applies "blk->doHeapRegion"
1209 // to each of the regions, by attempting to claim the region using the
1210 // HeapRegionClaimer and, if successful, applying the closure to the claimed
1211 // region.
1212 void heap_region_par_iterate(HeapRegionClosure* cl,
1213 uint worker_id,
1214 HeapRegionClaimer* hrclaimer) const;
1215
1216 // Iterate over the regions (if any) in the current collection set.
1217 void collection_set_iterate(HeapRegionClosure* blk);
1218
1219 // Iterate over the regions (if any) in the current collection set. Starts the
1220 // iteration over the entire collection set so that the start regions of a given
1221 // worker id over the set active_workers are evenly spread across the set of
1222 // collection set regions.
1223 void collection_set_iterate_from(HeapRegionClosure *blk, uint worker_id);
1224
1225 HeapRegion* next_compaction_region(const HeapRegion* from) const;
1226
1227 // Returns the HeapRegion that contains addr. addr must not be NULL.
1228 template <class T>
1229 inline HeapRegion* heap_region_containing(const T addr) const;
1230
1231 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
1232 // each address in the (reserved) heap is a member of exactly
1233 // one block. The defining characteristic of a block is that it is
1234 // possible to find its size, and thus to progress forward to the next
1235 // block. (Blocks may be of different sizes.) Thus, blocks may
1236 // represent Java objects, or they might be free blocks in a
1237 // free-list-based heap (or subheap), as long as the two kinds are
1238 // distinguishable and the size of each is determinable.
1239
1240 // Returns the address of the start of the "block" that contains the
1241 // address "addr". We say "blocks" instead of "object" since some heaps
1242 // may not pack objects densely; a chunk may either be an object or a
1243 // non-object.
1244 virtual HeapWord* block_start(const void* addr) const;
1245
1246 // Requires "addr" to be the start of a chunk, and returns its size.
1247 // "addr + size" is required to be the start of a new chunk, or the end
1248 // of the active area of the heap.
1249 virtual size_t block_size(const HeapWord* addr) const;
1250
1251 // Requires "addr" to be the start of a block, and returns "TRUE" iff
1252 // the block is an object.
1253 virtual bool block_is_obj(const HeapWord* addr) const;
1254
1255 // Section on thread-local allocation buffers (TLABs)
1256 // See CollectedHeap for semantics.
1257
1258 bool supports_tlab_allocation() const;
1259 size_t tlab_capacity(Thread* ignored) const;
1260 size_t tlab_used(Thread* ignored) const;
1261 size_t max_tlab_size() const;
1262 size_t unsafe_max_tlab_alloc(Thread* ignored) const;
1263
1264 // Can a compiler initialize a new object without store barriers?
1265 // This permission only extends from the creation of a new object
1266 // via a TLAB up to the first subsequent safepoint. If such permission
1267 // is granted for this heap type, the compiler promises to call
1268 // defer_store_barrier() below on any slow path allocation of
1269 // a new object for which such initializing store barriers will
1270 // have been elided. G1, like CMS, allows this, but should be
1271 // ready to provide a compensating write barrier as necessary
1272 // if that storage came out of a non-young region. The efficiency
1273 // of this implementation depends crucially on being able to
1274 // answer very efficiently in constant time whether a piece of
1275 // storage in the heap comes from a young region or not.
1276 // See ReduceInitialCardMarks.
1277 virtual bool can_elide_tlab_store_barriers() const {
1278 return true;
1279 }
1280
1281 virtual bool card_mark_must_follow_store() const {
1282 return true;
1283 }
1284
1285 inline bool is_in_young(const oop obj);
1286
1287 virtual bool is_scavengable(const void* addr);
1288
1289 // We don't need barriers for initializing stores to objects
1290 // in the young gen: for the SATB pre-barrier, there is no
1291 // pre-value that needs to be remembered; for the remembered-set
1292 // update logging post-barrier, we don't maintain remembered set
1293 // information for young gen objects.
1294 virtual inline bool can_elide_initializing_store_barrier(oop new_obj);
1295
1296 // Returns "true" iff the given word_size is "very large".
1297 static bool is_humongous(size_t word_size) {
1298 // Note this has to be strictly greater-than as the TLABs
1299 // are capped at the humongous threshold and we want to
1300 // ensure that we don't try to allocate a TLAB as
1301 // humongous and that we don't allocate a humongous
1302 // object in a TLAB.
1303 return word_size > _humongous_object_threshold_in_words;
1304 }
1305
1306 // Returns the humongous threshold for a specific region size
1307 static size_t humongous_threshold_for(size_t region_size) {
1308 return (region_size / 2);
1309 }
1310
1311 // Returns the number of regions the humongous object of the given word size
1312 // requires.
1313 static size_t humongous_obj_size_in_regions(size_t word_size);
1314
1315 // Print the maximum heap capacity.
1316 virtual size_t max_capacity() const;
1317
1318 virtual jlong millis_since_last_gc();
1319
1320
1321 // Convenience function to be used in situations where the heap type can be
1322 // asserted to be this type.
1323 static G1CollectedHeap* heap();
1324
1325 void set_region_short_lived_locked(HeapRegion* hr);
1326 // add appropriate methods for any other surv rate groups
1327
1328 const G1SurvivorRegions* survivor() const { return &_survivor; }
1329
1330 uint survivor_regions_count() const {
1331 return _survivor.length();
1332 }
1333
1334 uint eden_regions_count() const {
1335 return _eden.length();
1336 }
1337
1338 uint young_regions_count() const {
1339 return _eden.length() + _survivor.length();
1340 }
1341
1342 uint old_regions_count() const { return _old_set.length(); }
1343
1344 uint humongous_regions_count() const { return _humongous_set.length(); }
1345
1346 #ifdef ASSERT
1347 bool check_young_list_empty();
1348 #endif
1349
1350 // *** Stuff related to concurrent marking. It's not clear to me that so
1351 // many of these need to be public.
1352
1353 // The functions below are helper functions that a subclass of
1354 // "CollectedHeap" can use in the implementation of its virtual
1355 // functions.
1356 // This performs a concurrent marking of the live objects in a
1357 // bitmap off to the side.
1358 void doConcurrentMark();
1359
1360 bool isMarkedNext(oop obj) const;
1361
1362 // Determine if an object is dead, given the object and also
1363 // the region to which the object belongs. An object is dead
1364 // iff a) it was not allocated since the last mark, b) it
1365 // is not marked, and c) it is not in an archive region.
1366 bool is_obj_dead(const oop obj, const HeapRegion* hr) const {
1367 return
1368 hr->is_obj_dead(obj, _cm->prevMarkBitMap()) &&
1369 !hr->is_archive();
1370 }
1371
1372 // This function returns true when an object has been
1373 // around since the previous marking and hasn't yet
1374 // been marked during this marking, and is not in an archive region.
1375 bool is_obj_ill(const oop obj, const HeapRegion* hr) const {
1376 return
1377 !hr->obj_allocated_since_next_marking(obj) &&
1378 !isMarkedNext(obj) &&
1379 !hr->is_archive();
1380 }
1381
1382 // Determine if an object is dead, given only the object itself.
1383 // This will find the region to which the object belongs and
1384 // then call the region version of the same function.
1385
1386 // Added if it is NULL it isn't dead.
1387
1388 inline bool is_obj_dead(const oop obj) const;
1389
1390 inline bool is_obj_ill(const oop obj) const;
1391
1392 G1ConcurrentMark* concurrent_mark() const { return _cm; }
1393
1394 // Refinement
1395
1396 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; }
1397
1398 // Optimized nmethod scanning support routines
1399
1400 // Register the given nmethod with the G1 heap.
1401 virtual void register_nmethod(nmethod* nm);
1402
1403 // Unregister the given nmethod from the G1 heap.
1404 virtual void unregister_nmethod(nmethod* nm);
1405
1406 // Free up superfluous code root memory.
1407 void purge_code_root_memory();
1408
1409 // Rebuild the strong code root lists for each region
1410 // after a full GC.
1411 void rebuild_strong_code_roots();
1412
1413 // Partial cleaning used when class unloading is disabled.
1414 // Let the caller choose what structures to clean out:
1415 // - StringTable
1416 // - SymbolTable
1417 // - StringDeduplication structures
1418 void partial_cleaning(BoolObjectClosure* is_alive, bool unlink_strings, bool unlink_symbols, bool unlink_string_dedup);
1419
1420 // Complete cleaning used when class unloading is enabled.
1421 // Cleans out all structures handled by partial_cleaning and also the CodeCache.
1422 void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred);
1423
1424 // Redirty logged cards in the refinement queue.
1425 void redirty_logged_cards();
1426 // Verification
1427
1428 // Perform any cleanup actions necessary before allowing a verification.
1429 virtual void prepare_for_verify();
1430
1431 // Perform verification.
1432
1433 // vo == UsePrevMarking -> use "prev" marking information,
1434 // vo == UseNextMarking -> use "next" marking information
1435 // vo == UseMarkWord -> use the mark word in the object header
1436 //
1437 // NOTE: Only the "prev" marking information is guaranteed to be
1438 // consistent most of the time, so most calls to this should use
1439 // vo == UsePrevMarking.
1440 // Currently, there is only one case where this is called with
1441 // vo == UseNextMarking, which is to verify the "next" marking
1442 // information at the end of remark.
1443 // Currently there is only one place where this is called with
1444 // vo == UseMarkWord, which is to verify the marking during a
1445 // full GC.
1446 void verify(VerifyOption vo);
1447
1448 // WhiteBox testing support.
1449 virtual bool supports_concurrent_phase_control() const;
1450 virtual const char* const* concurrent_phases() const;
1451 virtual bool request_concurrent_phase(const char* phase);
1452
1453 // The methods below are here for convenience and dispatch the
1454 // appropriate method depending on value of the given VerifyOption
1455 // parameter. The values for that parameter, and their meanings,
1456 // are the same as those above.
1457
1458 bool is_obj_dead_cond(const oop obj,
1459 const HeapRegion* hr,
1460 const VerifyOption vo) const;
1461
1462 bool is_obj_dead_cond(const oop obj,
1463 const VerifyOption vo) const;
1464
1465 G1HeapSummary create_g1_heap_summary();
1466 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats);
1467
1468 // Printing
1469 private:
1470 void print_heap_regions() const;
1471 void print_regions_on(outputStream* st) const;
1472
1473 public:
1474 virtual void print_on(outputStream* st) const;
1475 virtual void print_extended_on(outputStream* st) const;
1476 virtual void print_on_error(outputStream* st) const;
1477
1478 virtual void print_gc_threads_on(outputStream* st) const;
1479 virtual void gc_threads_do(ThreadClosure* tc) const;
1480
1481 // Override
1482 void print_tracing_info() const;
1483
1484 // The following two methods are helpful for debugging RSet issues.
1485 void print_cset_rsets() PRODUCT_RETURN;
1486 void print_all_rsets() PRODUCT_RETURN;
1487
1488 public:
1489 size_t pending_card_num();
1490
1491 protected:
1492 size_t _max_heap_capacity;
1493 };
1494
1495 class G1ParEvacuateFollowersClosure : public VoidClosure {
1496 private:
1497 double _start_term;
1498 double _term_time;
1499 size_t _term_attempts;
1500
1501 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); }
1502 void end_term_time() { _term_time += os::elapsedTime() - _start_term; }
1503 protected:
1504 G1CollectedHeap* _g1h;
1505 G1ParScanThreadState* _par_scan_state;
1506 RefToScanQueueSet* _queues;
1507 ParallelTaskTerminator* _terminator;
1508
1509 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
1510 RefToScanQueueSet* queues() { return _queues; }
1511 ParallelTaskTerminator* terminator() { return _terminator; }
1512
1513 public:
1514 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
1515 G1ParScanThreadState* par_scan_state,
1516 RefToScanQueueSet* queues,
1517 ParallelTaskTerminator* terminator)
1518 : _g1h(g1h), _par_scan_state(par_scan_state),
1519 _queues(queues), _terminator(terminator),
1520 _start_term(0.0), _term_time(0.0), _term_attempts(0) {}
1521
1522 void do_void();
1523
1524 double term_time() const { return _term_time; }
1525 size_t term_attempts() const { return _term_attempts; }
1526
1527 private:
1528 inline bool offer_termination();
1529 };
1530
1531 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP